Arwel Robson's last-minute try saw Jersey lose 30-27 at Newport Gwent Dragons in the British & Irish Cup.
Dragons led 17-10 at half-time thanks to tries from Luc Jones and Adam Jones, with a Mark McCrea try and Aaron Penberthy's penalty for Jersey.
Jack Moates scored for Jersey early in the second half, Penberthy kicked a penalty and Jersey won a penalty try as they pulled out a 27-23 lead.
But Robson ran in with the final move of the game to seal a win for Dragons.
His try came after Aaron Penberthy missed with a penalty but the ball stayed in play - had it have gone over or reached touch the match would have been over.
"Yes I'm disappointed, we can't hide from that, but at the same time I'm really proud of the players' performance," Jersey head coach Harvey Biljon said.
"Pandy Park's a difficult place to come, difficult conditions, 80 minutes out there is worth 120 minutes any other weekend and I think there are lots of things to build on and our players will take a lot from that experience.
"We got ourselves in a position to win the game, not taking away from the fact that there were a lot of changes in the team, but also an opportunity for those guys to put their hand up and say 'I want to play in the Championship starting team', so from my point of view it's great stuff."